package com.yzd.learnjava.io;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.IntBuffer;
import java.nio.channels.FileChannel;

import com.yzd.learnjava.util.Print;


public class MappedIo {
	private static int numOfInts = 4000000;
	private static int numOfUbuffInts = 200000;
	private abstract static class Tester{
		private String name ;
		public Tester(String name) {
			this.name = name;
			
		}
		public void runTest() {
			Print.printnb("name : " + name);
			try {
				long start = System.nanoTime();
				test();
				double duration = System.nanoTime() - start;
				System.out.format("   %.2f\n", duration / 1.0e9);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		
		public abstract void test() throws IOException;
	}
	
	private static Tester[] testers = {
		new Tester("Stream Write") {
			@Override
			public void test() throws IOException {
				DataOutputStream dos = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(new File("temp.tmp"))));
				for(int i = 0 ; i < numOfInts ; i++) {
					dos.writeInt(i);
				}
				dos.close();
			}
		},
		
		new Tester("Mapped Write") {
			@Override
			public void test() throws IOException {
				FileChannel fc = new RandomAccessFile("temp.tmp","rw").getChannel();
				IntBuffer ib = fc.map(FileChannel.MapMode.READ_WRITE, 0, fc.size()).asIntBuffer();
				for(int i = 0 ; i < numOfInts ; i++) {
					ib.put(i);
				}
				fc.close();
			}
		},
		new Tester("Stream Read") {
			@Override
			public void test() throws IOException {
				DataInputStream dos = new DataInputStream(new BufferedInputStream(new FileInputStream(new File("temp.tmp"))));
				for(int i = 0 ; i < numOfInts ; i++) {
					dos.readInt();
				}
				dos.close();
			}
		},
		
		new Tester("Mapped Read") {
			@Override
			public void test() throws IOException {
				FileChannel fc = new RandomAccessFile("temp.tmp","rw").getChannel();
				IntBuffer ib = fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size()).asIntBuffer();
				while(ib.hasRemaining()) {
					ib.get();
				}
				fc.close();
			}
		},
		
		new Tester("Stream Read/Write") {
			@Override
			public void test() throws IOException {
				RandomAccessFile raf = new RandomAccessFile(new File("temp.tmp"), "rw");
				raf.write(1);
				for(int i = 0 ; i < numOfUbuffInts; i++) {
					raf.seek(raf.length() - 4);
					raf.write(raf.readInt());
				}
				raf.close();
			}
		},
		
		new Tester("Mapped Read/Write") {
			@Override
			public void test() throws IOException {
				FileChannel fc = new RandomAccessFile("temp.tmp","rw").getChannel();
				IntBuffer ib = fc.map(FileChannel.MapMode.READ_WRITE, 0, fc.size()).asIntBuffer();
				ib.put(0);
				for(int i = 1 ; i < numOfUbuffInts; i++) {
					ib.put(ib.get(i - 1));
				}
				fc.close();
			}
		},
	};
	
	public static void main(String[] args) {
		for(Tester tester : testers) {
			tester.runTest();
		}
	}
}
